JP4469766B2 - Electronic printer - Google Patents

Description

  The present invention relates to an electronic printer and a light source for an electronic printer using an EL display such as an organic / inorganic EL panel.

  In recent years, there has been known a color image forming method in which charging, image exposure, and reversal development are repeated on a photoconductor, and a color toner image is directly superimposed on the photoconductor and then transferred to a transfer material at once (KNC process). ).

  The feature of this process is that subtractive color mixing is performed in which the toner images are directly superimposed on the photoconductor, and the next latent image is formed on the toner image and developed. Image exposure can be performed from outside or inside the photoreceptor.

  In order to form a color image, subtractive color mixing that superimposes toner images is necessary. In the external image exposure method, since the toner image already exists on the photoreceptor, the image exposure wavelength is restricted.

  On the other hand, the method of performing image exposure of the second color from the inside of the photoconductor (internal image exposure) has a feature that a latent image can be formed without being affected by light shielding of the toner layer on the photoconductor. It is only necessary to correct the toner layer potential, and the degree of color correction is greatly reduced.

  As a photoreceptor for the internal image exposure method, a drum shape is a standard usage, and as an optical system, an LED head that is easier to align and miniaturize than a laser optical system is common. The drum diameter can be reduced by 30 to 40% compared to the external image exposure method. Further, since the image exposure from the inside of the drum is performed by the LED unit arranged inside the transparent drum, the alignment accuracy and the superposition of the toner image are improved.

  As described above, in the internal image exposure method, a small and high-speed color printer in which the alignment accuracy and the color superposition are improved in principle can be realized by the combination with the LED head which is a small optical system.

  In addition, the one-time transfer method has advantages that there are few toner image dust and misalignment, which is a problem in the transfer method, is suitable for high image quality, and there is no restriction on transfer paper.

  However, when the LED unit is used as a light source, it is necessary to collect light from the LED unit and perform main scanning (movement of the drum in the axial direction). Although the alignment accuracy is improved as compared with the external image exposure method, the writing timing of each color depends on the rotational speed accuracy of the drum. There is also a method in which the LED unit is used as a line light source and main scanning is omitted, but the accuracy of the arrangement of the LED point light sources is as low as about ± 50 μm and the pitch is rough, which is not suitable for a high-precision printer.

  In view of the above circumstances, an object of the present invention is to obtain an electronic printer that does not require an operation such as main scanning as a light source in the internal image exposure method and can significantly improve the alignment of each color.

The electronic printer of the present invention includes a photosensitive drum body, an internal light source wound around the outer peripheral surface of the photosensitive drum body, and a photosensitive layer provided on the outer peripheral surface of the internal light source. An adhesive for adhering the internal light source to the photosensitive drum body is provided between the outer peripheral surface of the photosensitive drum body and the internal light source. The internal light source includes a cathode layer including a cathode, an EL layer, a hole transport layer, an anode layer including an anode, a TFT layer including a driving transistor and a switching transistor that emit light when the EL layer is turned on. And a capacitor.
The cathode electrode layer, EL layer, hole transport layer, anode electrode layer, and TFT layer are laminated in this order from the outer peripheral surface side of the photosensitive drum body. The photosensitive layer includes a charge generation layer and a charge transport layer in order from the outer peripheral surface side of the photosensitive drum body. A plurality of anodes, drive transistors, and switch transistors are provided, and one drive transistor and one switch transistor are associated with one anode. One cathode is provided in common corresponding to the plurality of anodes. When the switching transistor is turned on, a potential is stored in the capacitor, and a latent image is formed on the photosensitive layer by light emission from the EL layer.

  The electronic printer according to the present invention is characterized in that a potential difference is generated between each of the plurality of anodes and the cathode when the drive transistor is turned on.

  The electronic printer of the present invention further includes a scanning line and a signal line, and a signal supplied from the signal line is supplied to the capacitor via the switching transistor.

  Since the pixel array used as the light source is provided on the entire circumference of the drum, the relative position between the position of each pixel and the position of the drum peripheral surface always coincides, so only by managing the pixels arranged in a matrix, The image positions of a plurality of colors do not shift.

  Furthermore, since it is on the entire circumference of the drum, all exposure methods such as surface exposure, scanning exposure, and slit exposure can be supported. In the present invention, an image having a predetermined circumferential width is formed at a time, and each time development of one color is completed, an image corresponding to the next color is formed for each image of the predetermined width. Yes. As a result, development of a plurality of colors can be performed with one rotation of the drum, and images of a plurality of colors can be superimposed on the drum. Since the superimposed images are transferred to a transfer material at the transfer unit, and are fixed and discharged at the fixing unit, processing of one image is extremely short compared with the conventional multi-rotation method and the tandem method.

  As described above, the digital printer according to the present invention does not require an operation such as main scanning as a light source in the internal image exposure method, and has an excellent effect that the alignment of each color can be remarkably improved.

  FIG. 1 shows an internal image exposure digital printer 100 according to the present embodiment.

  The upper part of the casing 102 is an engine unit 104, and various parts necessary for image formation are assembled. A paper feed tray 106 is provided at the lower part of the casing 102. A sheet material 108 is accommodated in the paper feed tray 106. A sheet feeding device (not shown) that feeds the stacked sheet materials 108 one by one from the uppermost layer is disposed above the sheet feeding tray 106. As a result, the sheet material 108 is sandwiched and conveyed between the conveyance roller pair 110 and 112 and sent to the engine unit 102.

  A photosensitive drum 114 is disposed in the engine unit 102. The photosensitive drum 114 rotates at a constant speed in the clockwise direction of FIG.

On the peripheral surface of the photosensitive drum 114, a charge generation layer 116 and a charge transport layer 118 (see FIG. 2, both of which will be described in detail later) are provided in layers, and can store charges (charging).

  Around the photosensitive drum 114, a charging unit 120 for each of a plurality of colors (CMYK) and a developing unit 122 are disposed. The arrangement order is the Y color charging unit 120Y, the Y color developing unit 122Y, the M color charging unit 120M, the M color developing unit 122M, and the C color along the clockwise direction of the photosensitive drum 114. The charging unit 120C for color, the developing unit 122C for C color, the charging unit 120K for K color, and the developing unit 122K for K color. Each charging unit 120 charges the surface of the photosensitive drum 114 positively, and the developing unit 122 supplies negatively charged toner. That is, a latent image of each color is formed on the photosensitive drum 114 by an internal light source 124 described later in an area between the charging unit 120 and the developing unit 122 for each color.

  Further, the sheet material 108 is conveyed to a transfer unit 126 provided in the lower part of the photosensitive drum 114 in FIG. 1, proceeds along the tangential direction of the photosensitive drum 114, and is transferred to the photosensitive drum 114 with a predetermined pressure in the transfer unit 126. It is conveyed while being pressed. At the time of pressing, a predetermined positive voltage for attracting negatively charged toner is applied.

  When the transfer at the transfer unit 126 is completed, the photosensitive drum 114 continues to rotate and passes through the cleaner unit 128, whereby the peripheral surface is cleaned and returns to the initial charging position.

  In other words, in this embodiment, a single rotation of the photosensitive drum 114 can develop and transfer a plurality of colors necessary for a full color image.

  The sheet material 108 that has passed through the transfer unit 126 is conveyed to the fixing unit 130 where the heat transferred at a predetermined temperature and the toner transferred at a predetermined pressure is fixed, discharged from outside the casing 102, and sent onto the discharge tray 132. It is done.

Inside the charge generation layer 116 and the charge transport layer 118 provided on the peripheral surface of the photosensitive drum 114, the planar internal light source array 124 is provided along these layers.
(Internal light source structure)
FIG. 2 shows a partial cross-sectional structure of the outer periphery of the photosensitive drum 114.

  An EL pixel array 134 as an internal light source array 124 is wound and attached to the outer peripheral portion 114 </ b> A of the drum body via an adhesive layer 132.

The EL pixel array 134 has a cathode electrode layer 136 (made of aluminum lithium alloy), a fluorescent material layer 137, and a hole transport layer 138 (based on the light emitting material layer 137 and the hole transport layer 138) from the adhesive layer 132 side. The interlayer insulating film 140, the adhesive layer 142 (SiO ₂ ), the anode electrode layer 143, and the TFT layer 144 are sequentially provided. After the EL pixel array is attached to the drum body, a coat layer 145 is formed on the surface of the drum body, and a charge generation layer 116 and a charge transport layer 118 are sequentially formed to complete the photosensitive drum 114.

  As shown in FIGS. 3 and 5, the TFT layer 144 is divided into a pixel portion 144P and a circuit portion 144C. The pixel portion 144P is divided into a matrix and can independently control the light emission of the fluorescent material. It is an aggregate of various pixels. The circuit unit 144C is a driver for performing light emission control of the pixel, and is disposed across two adjacent sides (X driver unit 144CX and Y driver unit 144CY) of the TFT layer 144. Note that the X driver portion 144CX in the circuit portion 144C of the TFT layer 144 is positioned below the overlap when the EL display body 134 is wound, so that almost the entire circumference of the drum is a chargeable region (see FIG. 3). . Note that a rounded step is generated in the overlapped portion when it is normal, but a smooth surface without a step is obtained by devising the layer structure of the overlap. Although there is almost no gap at the joint, it is preferable that the joint line be the drum rotation initial position.

  A circuit 144A shown in FIG. 4R> 4 is embedded in the pixel portion 144P of the TFT layer 144.

  In this circuit 144A, the scanning line 146 is a line that transmits a signal from the Y driver unit 144CY, and the signal line 148 is a line that transmits a signal from the X driver unit 144CX, and emits light based on the coordinates x and y. By selecting a pixel, a desired pixel can emit light with a predetermined gradation. The capacitor line 150 is a means for giving a reference potential of the capacitor, and the potential from the signal line is stored in the capacitor 151.

  Here, as shown in FIG. 5, each circuit 144 </ b> A on the pixel portion 144 </ b> P is controlled by the circuit portion 144 </ b> C of the TFT layer 144. That is, the switching transistor 152 is turned on, and a signal potential is stored in the capacitor 151, which turns on the driving transistor 154. In this manner, a potential difference is generated between the anode on the drive TFT 154 and the cathode electrode layer 136, and the fluorescent material layer 137 sandwiched between these portions is configured to emit light. The hole transport layer 138 is a layer for facilitating injection of holes from the anode into the EL layer 137. In the present embodiment, the color is visible light, and gradation is expressed based on voltage information from each signal line.

  In the above embodiment, the EL pixel array 134 is formed through the steps described in order from the top of FIG. The order of the process is peeling layer formation → TFT element formation → interlayer insulating film formation → contact hole formation → transparent electrode layer formation → bank formation → hole transport layer formation → EL layer formation → electrode layer formation.

  The release layer is formed of, for example, amorphous Si: H, and when irradiated with laser light, the part is peeled off and the EL pixel array can be peeled off from the base. The peeled EL pixel array 134 is wound around and pasted on the drum body as shown in FIG. Thereafter, the coat layer 145, the charge generation layer 116, and the charge transport layer 118 are sequentially formed to become the photosensitive drum 114.

  In the internal light source having the above-described configuration, pixels at fixed positions exist on the peripheral surface of the photosensitive drum 114, so that a latent image can be formed with no misregistration of images of a plurality of colors.

  The latent image is formed in the order of charging by the charging unit 120Y for the first color (Y color) when the initial position of the photosensitive drum 114 passes the cleaner unit 128 while rotating the photosensitive drum 114 at a constant speed. Then, after forming a latent image with the light from the internal light source 124 based on the image signal for Y color and developing it with the developing unit 122Y, it is charged with the charging unit 120M for the next color (M color), Rewriting the latent image based on the M color image signal is performed for all colors. That is, charging and development of each color can proceed simultaneously during image formation.

  The operation of this embodiment will be described below.

  When there is a print instruction, first, the photosensitive drum 114 is rotated to detect the initial position, that is, the time when the end seam that overlaps the X driver unit 144CX passes through the cleaner unit 128 when the EL display 134 is rotated. To do.

  From this time point, the clock is started, and charging of each color, latent image formation (EL emission), and development (toner supply) are started after timings ty seconds, tm seconds, tc seconds, and tk seconds. The timings ty seconds, tm seconds, tc seconds, and tk seconds are determined by the amount of movement from the initial position to the charging unit 120 of each color and the linear velocity of the photosensitive drum 114, and each charging unit 120 has an equal pitch. In this case, each time interval difference α is equal. That is, charging of the charging unit 120y is started ty seconds after passing through the initial position, charging of the charging unit 120M is started after elapse of a certain time α (after tm after passing through the initial position), and for a certain time. Charging of the charging unit 120C is started after a lapse of α (tc seconds after passing through the initial position), and charging of the charging unit 120K is performed after a lapse of a certain time α (after tk seconds after passing through the initial position). Start.

  In synchronization with the initial position of the photosensitive drum 114 passing through the transfer unit 126, the sheet material 108 is taken out from the paper feed tray 106, and the leading end enters the transfer unit 126. For this reason, the toner of each color is superposed on the image area of the photosensitive drum 114 to which the toner is attached in an overlapping manner, and is held at a predetermined pressure. At this time, a positive potential is generated in the transfer unit 126, and the negatively charged toner is easily transferred to the sheet material 108. As a result, the toner is reliably transferred to the sheet material 108.

  The sheet material 108 is conveyed to the fixing unit 130 in the next process, subjected to a fixing process, and then discharged to the discharge tray 132. In addition, the photosensitive drum 114 reaches an initial position to the cleaner unit 128 and waits for the next print instruction.

  According to the present embodiment, the EL pixel array 134 is attached to the entire circumference along the peripheral surface of the photosensitive drum 114 to form the internal light source 124, and the entire image forming area of the photosensitive drum 114 can be controlled by the TFT layer 144. Therefore, a mechanism for moving in the main scanning direction is not required as in the case of an internal light source using a conventional LED, and there is no element that shifts the image position for each color. For this reason, in a full-color image, there is no color shift etc., and a high quality image can be obtained.

  Further, according to the image forming control, there is a time when each color is charged, latent image formed, and developed at the same time, and accordingly, the processing time can be shortened as compared with the conventional multi-rotation type and tandem type exposure methods. it can.

  In the present embodiment, a flat bed type exposure unit is used, and the EL pixel array 134 on the lower surface side is provided as a light source, and a charging unit, a developing unit, a transfer unit, and a fixing unit for each color are provided on the upper surface side. An image may be formed while moving the bet-type exposure unit left and right at a constant speed, and a thin digital printer can be realized.

1 is a schematic structural diagram of a digital printer according to an embodiment. It is sectional drawing of the outer peripheral part containing the internal light source provided in the outer periphery of the drum. (A) is a perspective view which shows the surrounding state of a TFT layer, (B) is a front view which shows the surrounding state of a TFT layer. It is a circuit diagram provided in each pixel part of a TFT layer. It is an expanded view which shows the arrangement state of the pixel on a drum, and a circuit diagram. It is a manufacturing process figure of EL display body.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Digital printer 114 Photosensitive drum 120 Charging part 122 Developing part 124 Internal light source 134 EL display body 144 TFT layer 144P Pixel part 144C Circuit part 144CX X driver part 144CY Y driver part

Claims (3)

  A photosensitive drum body;
  An internal light source wound around the outer peripheral surface of the photosensitive drum body;
  A photosensitive layer provided on the outer peripheral surface of the internal light source,
  Between the outer peripheral surface of the photosensitive drum body and the internal light source, an adhesive for attaching the internal light source to the photosensitive drum body is provided,
  The internal light source is
    A cathode electrode layer including a cathode; and
    An EL layer;
    A hole transport layer;
    An anode electrode layer including an anode;
    A TFT layer including a drive transistor and a switch transistor that emit light when the EL layer is turned on;
    A capacitor, and
  The cathode electrode layer, the EL layer, the hole transport layer, the anode electrode layer, and the TFT layer are laminated in this order from the outer peripheral surface side of the photosensitive drum body,
  The photosensitive layer, in order from the outer peripheral surface side of the photosensitive drum body, includes a charge generation layer and a charge transport layer,
  A plurality of the anodes, the drive transistors, and the switch transistors are provided, and one drive transistor and one switch transistor are associated with one anode.
  The cathode is provided in common corresponding to the plurality of anodes,
  When the switch transistor is turned on, a potential is stored in the capacitor, and the latent image is formed on the photosensitive layer by light emission from the EL layer.
  Electronic printer. The electronic printer according to claim 1.
When the drive transistor is turned on, a potential difference is generated between each of the plurality of anodes and the cathode,
An electronic printer characterized by The electronic printer according to claim 2 .
Furthermore, a scanning line and a signal line are included,
A signal supplied from the signal line is supplied to the capacitor via the switch transistor;
An electronic printer characterized by

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